The effects of hydrogen annealing on carbon nanotube field‐effect transistors

Abstract

We have systematically investigated the effects of hydrogen annealing on Ni‐ and Alcontacted carbon nanotube field‐effect transistors (CNTFETs), whose work functions have not been affected by hydrogen annealing. Measured results show that the electronic properties of singlewalled carbon nanotubes are modified by hydrogen adsorption. The Ni‐contacted CNTFETs, which initially showed metallic behavior, changed their p‐FET behavior with a high on‐current over 10 μA after hydrogen annealing. The on‐current of the as‐made p‐FETs is much improved after hydrogen annealing. The Al‐contacted CNTFETs, which initially showed metallic behavior, showed unipolar p‐FET behavior after hydrogen annealing. We analyzed the energy band diagrams of the CNTFETs to explain experimental results, finding that the electron affinity and the bandgap of single‐walled carbon nanotubes changed after hydrogen annealing. These results are consistent with previously reported ab initio calculations.